PEOPLE who work as domestic cleaners are at an increased risk of asthma and other breathing problems, research claims.

A study of more than 4,500 women in Spain found that working as a cleaner in someone else's home at some point during their life was linked to a significantly higher risk of all respiratory illnesses compared with those who had never worked as cleaners.

The researchers suggested that the impact probably stretched to those cleaning their own homes, who were also exposed to a variety of cleaning products, dust and dirt.

Asthma is the most common lung disease acquired in the workplace in industrialised countries, said to account for up to 20% of cases in adults.

The team from the Municipal Institute of Medical Research in Barcelona said the study was the first to specifically assess the risk of asthma in women working as domestic cleaners.

They asked the women about their respiratory symptoms, whether they had been diagnosed or treated for asthma in the previous year and if they had ever been paid to clean someone else's home.

Of the 4,521 women, four out of 10 had worked as a domestic cleaner at some point and 593 (13%) were currently employed in domestic cleaning work.

The researchers found that one in eight women had asthma, while one in six had bronchitis.

They found that rates of respiratory symptoms which could be attributed to work among domestic cleaners were more than double those ofother jobs - 12% among current and former cleaners and 5% among those who hadnever worked as cleaners.

Among those not working as cleaners in people's homes, women working in hospitals and health-care centres had a significantly higher risk of asthma and bronchitis.

There was a slightly higher risk among those cleaninghotels, laboratories and kitchens, although not significantly so. The researchers concluded that working as an office cleaner was not associated with an increased risk of respiratory problems.

Writing in the journal Thorax, they said, "Domestic cleaning workers are exposed to a large variety of cleaning products containing both irritants and sensitisers, as well as indoor allergens.

"Consequently it can be hypothesised that the onset or aggravation of asthma in domestic cleaners could be related to an irritant-induced mechanism or to specific sensitisation."

The researchers suggested that the higher asthma risk among former cleaners compared to current cleaners could be due to those getting the condition being more likely to leave the job.

They estimated that 25% of the asthma cases in their study could be attributed to having a history of domestic cleaning work.